The X-ray CT device carries out X-ray photography while an X-ray tube and an X-ray detector arranged facing each other with a subject on a top plate rotate around the subject.
By means of X-ray photography, data (CT value) on the subject is accumulated, and characteristics of the subject are diagnosed based on the CT value.
The CT value is expressed by a “mass attenuation coefficient”*“density”. The “mass attenuation coefficient” is a value peculiar to substances. Accordingly, depending on the density state of the substance, there are times in which there is no difference in the CT value even when the substances are different, and which it is difficult to discriminate the substance based on the CT value.
The CT Dual Energy Scan method accumulates data on a subject using different tube voltages as a means of solving such phenomenon. The accumulated data may be referred to as projection data, accumulated data, or raw data.
This method includes a dual-source method, Photon Counting method, and rapid kV switching method.
One example of the rapid kV switching method accumulates data while switching the tube voltage per 1 view between a high voltage (140 kV) and a low voltage (80 kV). The switching frequency of the tube voltage may be referred to as the switching cycle.
The view count per one rotation is proportional to the resolution of the image; therefore, in order to obtain a high resolution tomographical image, the switching cycle must be shortened accordingly when the revolving speed is fast.
However, there is limit to the switching cycle regarding the rapid kV switching method; wherein, if the revolving speed is fast, the switching cycle cannot be shorted accordingly, resulting in problems of the view count per one rotation being insufficient, not being able to obtain sufficient resolution, and not being able to obtain high resolution tomographical images.
The present embodiment solves the abovementioned problems with the purpose of providing an X-ray CT device that obtains high resolution tomographical images by obtaining sufficient resolution even when the revolution speed is fast.